During World War Two, if one single weapon in Germany's arsenal can be said to have come closest to winning the war for the Third Reich, it was without doubt the U-Boat. German U-Boat technology, training, tactics and combat successes far exceeded those of any of the other combatant nations, and even as the Third Reich was crumbling, technically advanced vessels such as the Type XXI, many years ahead of its time, were being put into volume production. U-Boat crewmen were predominantly volunteers throughout the war, and selection procedures were rigorous in the extreme, resulting in the U-Boat Waffe taking much of the cream of Germany's naval personnel. Mention of U-Boats almost invariably brings to mind the great aces of World War Two, with the equally exceptional achievements of the U-Boat aces of World War One often forgotten. However, what was probably the greatest single achievement in submarine warfare, the sinking of three major enemy warships by one German U-Boat in a single engagement, occurred during World War One, perpetrated by the greatest ace of all time - Korvettenkapitän Lothar Arnauld de lar Periere. Gordon Williamson details the achievements of the U-Boat Waffe in both wars, together with a study of the uniforms and insignia worn by U-Boat crews accompanied by illustrations by Darko Pavlovic.